The present disclosure relates to systems and methods for manufacturing products from beryllium-containing compositions using additive manufacturing techniques. This permits complex, light-weight, and rigid parts comprising beryllium and alloys thereof to be made cheaply compared to other processes, and also permits rapid construction of such parts.
Additive Manufacturing (AM) is a new production technology for the rapid and flexible production of prototype parts, end-use parts, and tools directly from a digital model. AM makes three-dimensional (3D) solid objects of virtually any shape from a digital model. Generally, this is achieved by creating a digital blueprint of a desired solid object with computer-aided design (CAD) modeling software and then slicing that virtual blueprint into very small digital cross-sections/layers. Each layer begins with a thin distribution of powder spread over the surface of a bed or platform. The powder is selectively joined where the object is to be formed. A piston that supports the bed/platform within a build box lowers so that the next powder layer can be spread and selectively joined. This sequential layering process repeats within an AM machine (such as a three-dimensional printer) to build up the desired part. Following heat treatment, unbound powder is removed, leaving the semi-fabricated part.
AM has many advantages, including dramatically reducing the time from design to prototyping to commercial product. Demonstration units and parts can be rapidly produced. Parts can be created of any geometry, and generally out of any material, including ceramics, metals, polymers, and composites. Local control can be exercised over the material composition, microstructure, and surface texture. Running design changes are possible. Multiple parts can be built in a single assembly. No complicated potentially one-time die or tooling needs to be made before a prototype can be produced. Minimal energy is needed to make these 3D solid objects. It also decreases the amount of waste and raw materials. AM also facilitates production of extremely complex geometrical parts. Support material can be used to create overhangs, undercuts, and internal volumes. AM also reduces the parts inventory for a business since parts can be quickly made on-demand and on-site.
Two conventional AM methods include electron beam melting and laser sintering. In electron beam melting, after the deposition of metal powder, the loose metal powder cross-section is melted or fused by an electron beam. In laser sintering, a laser beam is used to sinter areas of the loosely compacted metal powder cross-section. The term “sintering” refers to the process by which particulates adhere into a solid mass due to externally applied energy. Laser sintering will also fuse a given cross-section with the already-sintered cross-section beneath. The metal powder that is not struck by the laser beam remains loose and falls away from the finished part when removed from the AM machine. Alternatively, the finished part can be depowdered by vacuuming or using a fluid such as compressed air to wash the finished part and dislodge any loose powder. Subsequent finishing steps may also be applied to the part to produce the characteristics desired. Such steps include, but are not limited to, further curing, sintering, infiltration, annealing, and final surface finishing.
A third AM method includes binder jetting. In binder jetting, after the deposition of metal powder, a liquid binding agent is selectively deposited to bond powder particles together. The finished part is developed through the layering of powder and binder. Binder jetting may result in a green finished part. The term “green part” refers to articles or preforms which are produced to be further processed with other manufacturing techniques. For example, metal green parts are further processed by sintering in an oven and infiltrating with at least one metal. The infiltration fills voids within the sintered preform.
Beryllium is a metal with highly desirable properties. These include high stiffness (Young's modulus=287 GPa), low density (1.85 g/cc), a high elastic modulus (130 GPa), high specific heat (1925 J/kg·K), high thermal conductivity (216 W/m·K), and a low coefficient of linear thermal expansion (11.4×106/°K). As a result, beryllium and its composites are useful in airborne and spaceborne structures, high-performance engines and brakes, and electronic components for thermal performance and vibration damping. Beryllium and its composites are also useful in combustion applications, hypersonic vehicles, and nuclear energy growth applications.
Additionally, articles made from beryllium and beryllium intermetallics have many advantages over other metals, such as titanium and titanium alloys, including a high specific modulus and a higher temperature range for continuous usage.
However, other properties of beryllium make it difficult to make parts and structures from beryllium using AM techniques. Beryllium readily oxidizes and reacts with carbon, nitrogen, and other materials. In its molten state, beryllium also undergoes rapid grain growth. In addition, such materials are typically brittle at room temperature, which is due in part to their complex crystal structures. As a result, AM techniques which require local melting of the metal powder, like electron beam melting and laser sintering, cannot be easily applied to beryllium. It would be desirable to provide additive manufacturing techniques that can be applied to beryllium-containing compositions.